rein

American  

[reyn] / reɪn /

noun

1. Often a leather strap, fastened to each end of the bit of a bridle, by which the rider or driver controls a horse or other animal by pulling so as to exert pressure on the bit.

2. any of certain other straps or thongs forming part of a harness, as a checkrein.

3. any means of curbing, controlling, or directing; check; restraint.

4. reins, the controlling or directing power.

   the reins of government.

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verb (used with object)

1. to check or guide (a horse or other animal) by exerting pressure on a bridle bit by means of the reins.

2. to curb; restrain; control.

   Synonyms:

   limit, bridle, check

verb (used without object)

1. to obey the reins.

   a horse that reins well.

2. to rein a horse or other animal.

idioms

1. give rein to, to give complete freedom to; indulge freely: Also give free rein to, give full rein to.

   to give rein to one's imagination.

2. draw rein, to curtail one's speed or progress; halt.

   The rider saw the snake and drew rein sharply.

rein British  

/ reɪn /

noun

1. (often plural) one of a pair of long straps, usually connected together and made of leather, used to control a horse, running from the side of the bit or the headstall to the hand of the rider, driver, or trainer

2. a similar device used to control a very young child

3. any form or means of control

   to take up the reins of government

4. the direction in which a rider turns (in phrases such as on a left ( or right ) rein , change the rein )

5. something that restrains, controls, or guides

6. to allow considerable freedom; remove restraints

7. to control carefully; limit

   we have to keep a tight rein on expenditure

8. with the reins held loosely so that the horse is relatively unconstrained

9. to take up the reins so that the distance between hand and bit is lessened, in order that the horse may be more collected

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verb

1. (tr) to check, restrain, hold back, or halt with or as if with reins

2. to control or guide (a horse) with a rein or reins

   they reined left

rein More Idioms  

1. see draw in the reins; free hand (rein) tight rein on.

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Other Word Forms

• reinless
  adjective
• unreined
  adjective

Etymology

Origin of rein

1300–50; (noun) Middle English rene, reine, raine < Old French re ( s ) ne < Vulgar Latin *retina, noun derivative of Latin retinēre to hold back, retain; (v.) Middle English rainen, reinen, derivative of the noun

Explanation

Rein is both a noun and a verb for guiding and restraining. You can use the long strap, or rein, on a horse to control its speed and direction, and you can rein in your own tongue by closing your mouth. Rein rhymes with rain but the two words describe very different things. Rain comes down all over the place, uncontrolled, while a rein holds things in place or controls what comes out. As a noun, rein is often used as a plural word "reins" when talking about actual leather restraints used in horse riding, but a rein also is something non-physical like when you put a rein on spending by shopping less.

Example Sentences

As passionate as he has been about the needs to rein in AI, Pope Leo may find himself issuing a similar warning in the years ahead.

From BBC • May 25, 2026

The conflicts of interest and questionably moral options to bet on the misfortune of others has prompted many states to try and rein these platforms in.

From Salon • May 24, 2026

The majority dismissed Hamm as improvidently granted, sparing the life of the defendant, Joseph Smith, and rejecting Alabama’s request for freer rein to execute intellectually disabled people.

From Slate • May 23, 2026

Regarding the governments in such countries, there is "growing mistrust of their ability to rein in deficits", Kevin Thozet, a market analyst at French investment group Carmignac, told AFP.

From Barron's • May 20, 2026

She wound and unwound a strap of leather rein around a finger.

From "Throne of Glass" by Sarah J. Maas

Related Words

• curb
• repress
• restrict
• suppress